Changes in the patterns of inorganic nitrogen and TN/TP ratio and the associated mechanism of biological regulation in the shallow lakes of the middle and lower reaches of the Yangtze River

The changes of NH3-N, NO3-N, NO2-N and TN/TP were studied during growth and non-growth season in 33 subtropical shallow lakes in the middle and lower reaches of the Yangtze River. There were significant positive correlations among all nutrient concentrations, and the correlations were better in growth season than in non-growth season. When TP>0.1 mgL-1, NH3-N increased sharply in non-growth season with increasing TP, and NO3-N increased in growth season but decreased in non-growth season with TP. These might be attributed to lower dissolved oxygen and low temperature in non-growth season of the hypereutrophic lakes, since nitrification is more sensitive to dissolved oxygen and temperature than antinitrification. When 0.1 mgL-1>TP>0.035 mgL-1, TN and all kinds of inorganic nitrogen were lower in growth season than in non-growth season, and phytoplank-ton might be the vital regulating factor. When TP<0.035 mgL-1, inorganic nitrogen concentrations were relatively low and NH3-N, NO2-N had significant correlations with phytoplankton, indicating that NH3-N and NO2-N might be limiting factors to phytoplankton. In addition, TN/TP went down with decline in TP concentration, and TN and inorganic nitrogen concentrations were obviously lower in growth season than in non-growth season, suggesting that decreasing nitrogen (especially NH3-N and NO3-N) was an important reason for the decreasing TN/TP in growth season. The ranges of TN/TP were closely related to trophic level in both growth and non-growth seasons, and it is apparent that in the eutrophic and hypertrophic state the TN/TP ratio was obviously lower in growth season than in non-growth season. The changes of the TN/TP ratio were closely correlated with trophic levels, and both declines of TN in the water column and TP release from the sediment were important factors for the decline of the TN/TP ratio in growth season.     

Comparative study of 17 β-estradiol on endocrine disruption and biotransformation in fingerlings and juveniles of Japanese sea bass Lateolabrax japonicus

Estrogenic contaminants in the aquatic environment are associated with endocrine disruption and feminization in fish. The effects of endocrine disrupting chemicals (EDCs) on fish have been well documented. However, very few studies have focused on 17 β-estradiol (E2) and its effects on endocrine system and biotransformation in a single prolonged exposure. This study investigated changes in the levels of serotonin (5-hydroxytryptamine) and acetyl choline esterase (AchE) in brain, cortisol in plasma and Ethoxyresorufin-O-deethylase (EROD) activity in gill of two different size groups (fingerlings and juveniles) of Japanese sea bass (Lateolabrax japonicus) upon exposure to two sub-lethal concentrations (200 and 2000 ng L⁻¹) of E2 for 30 d. The results indicate that cortisol level and EROD activity significantly increased in both groups, whereas serotonin level increased in juveniles and decreased in fingerlings due to E2 exposure. The correlation analysis revealed that E2 significantly affected the endocrine and biotransformation systems in both age groups.     

Study of the Activity and Segmentation of Active Faults Using Measurements of Radon and Mercury Gases

In this paper,measurements of gaseous radon and gaseous mercury densities were conducted for the first time along the Haiyuan active fault zone,including three longer secondary shear faults from Biangou to Shaokou,faults in the Ganyanchi pull-apart basin,and the Biangou push-up structure as well as the thrust fault at the eastern pediment of Liupanshan Mountain in the terminal compressional area.Then relations between fracture gas densities and faulting activity were analyzed.The results show that there is a distinct corresponding relation between gaseous radon and gaseous mercury densities and faulting activity,when the measurement conditions are basically the same,and it proves that the fault gasmetry method is an effective technique for study the activity and segmentation of active faults.     

Method study of classification and gradation of earthquake disasters

Based on data of earthquake disaster events during 1954~2005 in the Chinese mainland, the classification and gradation of earthquake disasters have been studied by multivariate statistical analysis. Three fundamental structures of earthquake disasters have been found and an FAPE (factor analysis-principal component-equamax rotation) classification model and an HCWS (hierarchical cluster-ward method-seuclid) gradation model have been constructed. Earthquake disasters are divided into eight classes and five grades respectively in the models, which give a reasonable explanation to the phenomenon of earthquake disasters.     

Application of Fisher method to discriminating earthquakes and explosions using criterion m_b/M_S

Introduction Earthquake magnitude is a measurement of earthquake intensity, which is one of the basic seismic parameters. The body-wave magnitude mb and surface-wave magnitude MS are based re- spectively on different wave spectrum amplitudes, therefore, the magnitude used as a criterion has its sound physical basis, which is in fact to distinguish the frequency components of seismic waves excited by explosion and earthquake. The magnitude criterion has a very clear physical meaning. Proposed …     

Source mechanism of strong aftershocks (M_s≥5.6) of the 2008/05/12 Wenchuan earthquake and the implication for seismotectonics

Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedro...     

Investigation of Capable Fault and Identification of Diffuse Seismicity

Based on the author's experience in the siting of nuclear power plants,some important points and methods for investigation of capable fault and the identification of diffuse seismicity are discussed in the paper.     

Simulation of the active and quiet periods of seismicity

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Physical meaning and prediction efficiency of the load/unload response ratio of rocks in strain-weakening phase before failure

Introduction In studying the instability of a non-linear system, YIN (1987), YIN and YIN (1991), YIN, et al (1994), and Yin, et al (1994, 1995, 2000) have presented a concept of load/unload response ratio (LURR) of the system. When the system is in a stable state, its response process to the load/unload follows the same trajectory on the stress-strain diagram, and the load/unload response ratios are equal. However, when the system departs from a stable state, its response to the load/un…     

Soil characteristics and site effect assessment in the city of Delhi (India) using H/V and f–k methods

Local site conditions substantially affect the characteristics of seismic waves and its potential to cause earthquake damage. To accurately identify the variation of seismic hazard at different locations within the cities, measurements from a three-component station may be used for estimating the resonance frequencies and evaluate the expected level of damage at each site. This information can also be complemented with array measurements of ambient noise in order to estimate the V_s profiles and characterize the corresponding sediment layers at each site.     

Short-term and imminent anomalies of earthquake of load and unload response ratio of the well level to earth tides

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Causes and solutions of overshoot and undershoot and end swing in Hilbert-Huang transform

Introduction Hilbert-Huang transform (HHT) is a great break in processing nonlinear and non-stationary data and can be successfully used in many science domains. There are mainly two parts in this method. The first part is to decompose the original data into several intrinsic mode functions (IMF) with the empirical mode decomposition (EMD). IMF components are derived from the original data directly according to the local characteristics in the data under some rules, so that IMF are poste…     

Are ARM and TRM analogs? Thellier analysis of ARM and pseudo-Thellier analysis of TRM

We test the possibility of using the pseudo-Thellier method as a means of determining absolute paleointensity. Thellier analysis of anhysteretic remanent magnetization (ARM) and pseudo-Thellier analysis of thermoremanent magnetization (TRM) have been carried out on a large collection of sized synthetic magnetites and natural rocks. In all samples, the intensity of TRM is larger than that of ARM and the ratio R (=TRM/ARM) is strongly grain size dependent. The best-fit slope (b_TA) from pseudo-Thellier analysis of TRM shows a linear correlation with R. The ratio b_TA/R yielded approximately correct paleointensities, although uncertainties are larger than in typical Thellier-type determinations. For single-domain and multidomain magnetites, alternating field and thermal stabilities of ARM and TRM are fairly similar. However, for ∼0.24 μm magnetite, ARM is both much less intense and less resistant to thermal demagnetization than TRM, reflecting different domain states for the two remanences and resulting in severely non-linear Arai plots for Thellier analysis of ARM.     

Experiments of Brittle-Plastic Transition and Instability Modes of Juyongguan Granite at Different Temperatures and Pressures

INTRODUCTIONAlargenumberofstudiesindicatethatthelithosphericstresslimit (peakstrength)iscoincidentwiththefocaldepthofstrongearthquakes (Goetzeetal.,1 979;Braceetal.,1 980 ;Kirby ,1 980 ;Meissner ,etal.,1 982 ;Sibson ,1 982 ;Chenetal.,1 983;Smithetal.,1 984 ;andMeissner,1 996 ) ,whicharelocatedinrelativelyhigh velocityzonesabovelow velocityzonesinthecrust.Butthereexistsdifferenttheoriesconcerningthereasonsforthecoincidence ,especiallyconcerningthecontrollingfactorsaboutthefocaldepthofstr…     

Normalization of seismic quantities and units

In the seismological field, attention paid to the problem concerning the normalization of seismic quantities and their units has not been enough all along. In different countries, different seismological organizations and different academic periodicals, seismic quantities and their units are used according to different rules and are expressed in different forms. Some of such examples include that some units unapproved by the International Conference on (CGPM) and some units that can not be u…     

Characteristics of foreshock and its identi-fication

Introduction The characteristics of generalized foreshock and direct foreshock and their identification,as well as their application to medium and short-term prediction of strong earthquake is a major study objective in seismometry both in China and abroad.China has made many short-term and imminent earthquake predictions.Among the ones with clear hazard-mitigating effect and social manifestation,direct foreshock has made an obvious contribution,for example,the MS=7.2Menglian earthquake occu…     

Estimates of Current Helicity and Tilt of Solar Active Regions and Joy’s Law

Geomagnetism and Aeronomy - The tilt angle, current helicity and twist of solar magnetic fields can be observed in solar active regions. We carried out estimates of these parameters by two ways....     

Group velocity distribution of Rayleigh waves and crustal and upper mantle velocity structure of the Chinese mainland and its vicinity

Introduction A lot of results have been achieved on the study of crust and upper mantle structure in Chinese mainland by the surface wave dispersion. The seismometer can be classified into three types based on the development from the analog to digital instrument. FENG, et al (1981) measured the dispersion curves of group and phase velocity along 28 paths, with 19 earthquakes recorded by 15 base analog seismic stations, subdivided the Chinese mainland into 5 blocks and obtained the average c…     

Correlation between δ~(18)O,Sr/Ca and Mg/Ca of coral Acropora and seawater temperature from coral culture experiments

To be used as proxies of seawater surface temperature(SST), the δ 18Oc values and Sr/Ca and Mg/Ca ratios of scleractinian coral skeletons must be verified by coral culture experiments in the laboratory. This paper describes a coral culture experiment that was conducted at several seawater temperatures T(21–28°C) using a tandem aquarium system and the new method for depositing coral skeletons grown under controlled conditions. The δ 18Oc values and the Sr/Ca and Mg/Ca ratios of the cultured coral were measured. We concluded that the δ 18Oc values and Sr/Ca and Mg/Ca ratios of the cultured coral are clearly correlated with T. The linear regression curve is δ18Oc(‰)=δ0.1427δT(°C)δ0.1495(n=18, r=0.955, p0.0001), and the slope of δ0.1427‰/°C is at the low end of the range of published values(δ0.13–δ0.29‰/°C). The Sr/Ca ratio decreases with increasing T, whereas the Mg/Ca ratio increases with increasing T, indicating a negative correlation between Sr/Ca and Mg/Ca. Their linear regression curves are Sr/Ca(mmol/mol)=δ0.04156δT+10.59(n=15, r=0.789, p0.005) and Mg/Ca(mmol/mol)= 0.04974δT+2.339(n=17, r=0.457, p0.05), respectively, which demonstrate that when Mg/Ca and Sr/Ca are increased by one unit, T increases by 5.19°C and decreases by 15.62°C, respectively. These variations are significantly lower than published values.